src/class: fix init on dispatch of twice derived classes

dynamic_dispatch/_class.py

@@ -65,7 +65,7 @@ class Registered(wrap):
 
                     def __init__(self, *args, **kwargs):
                         # Certain scenarios can cause __init__ to be called twice. This prevents it.
-                        if not self.__dispatch_init:
+                        if self.__class__ == __class__ and not self.__dispatch_init:
                             return
 
                         self.__dispatch_init = False

tests/test_class.py

@@ -541,3 +541,31 @@ def __init__(self, a):
         self.assertEqual(obj.abc_count, 1)
         self.assertEqual(obj.a, 5)
         self.assertEqual(obj.a_count, 1)
+
+    def test_dispatch_twice_derived(self):
+        @dynamic_dispatch
+        class Foo(OneArgInit):
+            pass
+
+        @Foo.dispatch(on='bar')
+        class Bar(Foo):
+            def __init__(self, abc, d):
+                super().__init__(abc)
+                self.d = d
+                self.d_count = getattr(self, 'b_count', 0) + 1
+
+        @Foo.dispatch(on='baz')
+        class Baz(Bar):
+            def __init__(self, abc, d, e):
+                super().__init__(abc, d)
+                self.e = e
+                self.e_count = getattr(self, 'e_count', 0) + 1
+
+        obj = Foo('baz', 'd', 'e')
+        self.assertIsInstance(obj, Baz)
+        self.assertEqual(obj.abc, 'baz')
+        self.assertEqual(obj.abc_count, 1)
+        self.assertEqual(obj.d, 'd')
+        self.assertEqual(obj.d_count, 1)
+        self.assertEqual(obj.e, 'e')
+        self.assertEqual(obj.e_count, 1)